I think he meant that if someone that he has a form, and people can type in html, but he is replacing the http://'s with a hyperlink, but if somone types in an img tag, it will also replace the http with a hyperlink, so he wants to know how to find if it is part of an image tag, or if it should be turned into a hyperlink.

I would probably have to see some of your code, are you doing it with ereg, ereg_replace, substr_replace?